In many applications, electric discharge machining is used for the mass production of parts which must be machined to close tolerances. There are several factors which affect the repeatability of accuracy of machining by the EDM process including the process parameters of electrode size, spark energy, spark current, gap length, gap voltage and the wire guide used to direct the electrode to a workpiece. For example, when the EDM process is used to machine a small hole through a thin plate, the small dimensions of the wire electrode require a support system which is sufficiently accurate to support the electrode in all directions while providing smooth servo drive of the electrode through the wire guide.
One problem is that prior wire guides for directing electrodes with respect to a workpiece can frictionally engage the electrode in a manner to increase the observed vibration amplitude in the electrode tip during electric discharge machining of a hole in a workpiece.
Accordingly, there is a need to provide an improved low friction wire guide which will smooth the servo drive of an electrode wire as its tip is driven with respect to a workpiece to remove metal therefrom.
A general object of this invention is to provide an improved wire guide having low friction wire guide surfaces for smoothing wire electrode travel during electric discharge machining so as to obtain a high degree of repeatable accuracy in the machining of parts.